SQL - User-defined Functions
Overview
User-defined functions (UDFs) extend SQL with reusable scalar or table-valued logic.
-- MySQL UDFs require plugins or CREATE FUNCTION for stored functions
CREATE FUNCTION add_tax(subtotal DECIMAL(10,2)) RETURNS DECIMAL(10,2)
DETERMINISTIC
RETURN subtotal * 1.08;
SELECT add_tax(100.00);
DROP FUNCTION add_tax;
CREATE OR ALTER FUNCTION dbo.add_tax(@subtotal DECIMAL(10,2))
RETURNS DECIMAL(10,2)
AS
BEGIN
RETURN @subtotal * 1.08;
END
GO
SELECT dbo.add_tax(100.00);
DROP FUNCTION dbo.add_tax;
-- SQLite UDFs are provided by host apps (C/Python/etc.), not via SQL DDL.